1. Field of the Invention
The invention relates to a projectile receiving system for use in testing the integrity of a duct pipe serving as a housing for fiber optic cables. More particularly, the invention relates to a projectile receiver selectively attached to the terminal end of a duct pipe for safely receiving (and subsequently removing therefrom) a projectile that has been forced through the duct pipe under high pressure. The invention also relates to a method of using the device.
2. Description of the Prior Art
In the optical fiber industry, small diameter, high-density polyethylene plastic pipes are used as conduits or ducts for housing optical fibers. These duct pipes usually run for many miles, and either lay in bundles in a trench or are aggregated within a larger pipe. Optical fibers are subsequently positioned within these previously placed duct pipes.
It, therefore, becomes critical that the length of pipe be continuous and unobstructed such that there is no interference with the optical fibers as they are inserted within the duct pipes. The pipes are, therefore, tested prior to installing the optical fibers therein. Pipes are currently tested for continuity and lack of obstructions by passing a projectile, or "bird", having approximately the same diameter as the optical fiber through the pipe.
Specifically, the bird is placed in a first end of the pipe under high pressure of approximately 375 cfm. Under this high pressure and the force it exerts, the projectile, or bird, moves at high velocity through the pipe. Assuming the projectile reaches the terminal end of the pipe unencumbered, clear evidence is provided that the pipe is continuous and straight.
Such tests are performed every mile or so where a manhole, or a hand hole, is provided for accessing the pipe line. In practice, the projectile is inserted in one manhole (or hand hole) and exits at the next manhole (or hand hole) a mile or so away. This process is then repeated throughout the length of the pipe. Given the high speed of the projectile as it passes through the pipe, it is important to provide a safe system for stopping the projectile as it exits the duct pipe so that it does not cause damage to property or person.
The prior art addresses this problem by using things such as bales of hay situated near the manhole (or hand hole) opening. Upon exiting the duct pipe, the projectile impacts the hay bales, which impact is supposed to stop the flight of the projectile. The reality, however, is that the projectile often ricochets off the hay bales and causes damage during its wayward flight, both to property and to the body of the person overseeing the testing process.
As such, a need exists for a reliable, convenient and effective system for receiving, stopping and retrieving a high velocity projectile used in testing duct pipes. The projectile must be stopped in a safe manner and must be available for retrieval from the receiving device. The receiving device should be easily attached to and removed from the pipe being tested so it can be moved quickly from one pipe being tested to the next.